Question

A certain sum at a certain rate of SI amounts to 1125rs in 4 years and 1200rs in 7 years. Find the sum and rate of interest.

Answer 1

$\huge \dag \boxed{ \mathfrak{ \purple{Answer}}}$

1125 = P(1+r (4))

Equation 2:

1200=P(1+r(7))

Solution

( (1125/P )-1 )/4 = r

4800 = 7875 - 3P

-3075 = - 3P

P = (-3075) / (- 3)

P = 1025

Put value of  P in any equation

1125 = 1025(1+r (4))

1125/1025 = 1 +r (4)

1.0975 = 1 +r (4)

1.0975 -  1 = r (4)

0.0975 = r (4)

r= 0.0975 /4

r = 0.024

Rate of Interest per year as a percent

R = 0.024 ×100

R = 2.44